l-Alanylglycylhistamine dihydro­chloride

In the title compound {systematic name: 4-[2-({N-[(2S)-2-ammonio­propano­yl]glyc­yl}amino)­eth­yl]-1H-imidazol-3-ium dichloride}, C10H19N5O2 2+·2Cl−, the pseudo-tripeptide l-alanyl­glycyl­histamine is protonated at both the terminal amino group and the histidine N2 atom. The resulting positive charges are neutralized by two chloride anions. In the crystal, the organic cation adopts a twisted conformation about the CH2—CH2 bond of histamine and about the C—N bond in the main chain, stabilized by a short intra­molecular C—H⋯O contact. In the crystal, N+—H⋯O and N+—H⋯Cl− hydrogen bonds link the mol­ecules into infinite sheets parallel to the (100) plane. The stacking of these sheets along the a axis is supported by Namide—H⋯Cl− hydrogen bonds

Evidence for a soft-phonon-mode-driven Peierls-type distortion in Sc3_3CoC4_4

We provide experimental and theoretical evidence for the realization of the Peierls-type structurally distorted state in the quasi-one-dimensional superconductor Sc$_3$CoC$_4$ by a phonon-softening mechanism. The transition from the high- to the final low-temperature phase below 80K proceeds via an extended intermediate temperature regime between 80K and 150K characterized by phonon-driven atom displacements. In support of the low-dimensional character of the title compound we find a highly anisotropic correlation-length of these dynamic distortions.Comment: 9 pages, 7 figures and supporting informatio

Betulin Phosphonates; Synthesis, Structure, and Cytotoxic Activity

International audienceBetulin derivatives are a widely studied group of compounds of natural origin due to their wide spectrum of biological activities. This paper describes new betulin derivatives, containing a phosphonate group. The allyl-vinyl isomerization and synthesis of acetylenic derivatives have been reported. Structural identification of products as E and Z isomers has been carried out using 1 H-, 13 C-, 31 P-NMR, and crystallographic analysis. The crystal structure in the orthorhombic space group and analysis of crystal packing contacts for 29-diethoxyphosphoryl-28-cyclopropylpropynoyloxy-lup-20E(29)-en-3β-ol 8a are reported. All new compounds were tested in vitro for their antiproliferative activity against human T47D (breast cancer), SNB-19 (glioblastoma), and C32 (melanoma) cell lines

Modélisation des attaques de sulfate dans le béton

Dans ce travail, on se propose d'étudier la durabilité des matériaux du génie civil dans leur environnement, et plus principalement aux problèmes liés à la dégradation du béton soumis à des attaques de sulfate. Ce problème est sujet à de nombreuses interrogations sur l'origine de la dégradation des bétons dans de telles conditions. Nous nous intéressons à la formation d'ettringite lors de la réaction chimique entre une solution concentrée de sulfate de sodium et les constituants du béton, développant une pression sur la surface des pores de la pâte de ciment. Lorsque cette pression est suffisamment importante, on observe l'apparition de fissures dans la microstructure du béton. On note alors que le comportement du matériau cimentaire est fortement lié à la compréhension fine de l'évolution des propriétés de la microstructure. Sur la base d'essais expérimentaux, une étude numérique est réalisée pour modéliser les attaques de sulfates dans des bétons testés en laboratoire

Pas de Deux of an NO Couple: Synchronous Photoswitching from a Double-Linear to a Double-Bent Ru(NO)(2) Core under Nitrosyl Charge Conservation

The {Ru(NO)(2)}(10) dinitrosylruthenium complex [Ru(NO)(2)(PPh3)(2)] (1) shows photo-induced linkage isomerism (PLI) of a special kind: the two NO ligands switch, on photo-excitation, synchronously from the ground state (GS) with two almost linear RuNO functions to a metastable state (MS) which persists up to 230 K and can be populated to approximate to 50 %. The MS was experimentally characterised by photo-crystallography, IR spectroscopy and DS-calorimetry as a double-bent variant of the double-linear GS. The experimental results are confirmed by computation which unravels the GS/MS transition as a disrotatory synchronous 50 degrees turn of the two nitrosyl ligands. Although 1 shows the usual redshift of the N-O stretch on bending the MNO unit, there is no increased charge transfer from Ru to NO along the GS-to-MS path. In terms of the effective-oxidation-state (EOS) method, both isomers of 1 and the transition state are Ru-II(NO+)(2) species

4-{2-[3-(2-Ammonioacetamido)propanamido]ethyl}-1H-imidazol-3-ium dichloride

Mol­ecules of the title compound, Gly-β-Ala-Histamine dihydro­chloride, C10H19N5O2 2+·2Cl−, are linked by N—H⋯O and N—H⋯Cl hydrogen bonds into two-dimensional polymeric sheets parallel to the (011) plane, forming a stacked structure along the a axis. The parallel layers are also inter­linked alternately by different N—H⋯Cl hydrogen bonds, forming a three-dimensional framework

Partially Covalent Two-Electron/Multicentric Bonding between Semiquinone Radicals

International audienc

Cerebral organoids at the air-liquid interface generate diverse nerve tracts with functional output.

Neural organoids have the potential to improve our understanding of human brain development and neurological disorders. However, it remains to be seen whether these tissues can model circuit formation with functional neuronal output. Here we have adapted air-liquid interface culture to cerebral organoids, leading to improved neuronal survival and axon outgrowth. The resulting thick axon tracts display various morphologies, including long-range projection within and away from the organoid, growth-cone turning, and decussation. Single-cell RNA sequencing reveals various cortical neuronal identities, and retrograde tracing demonstrates tract morphologies that match proper molecular identities. These cultures exhibit active neuronal networks, and subcortical projecting tracts can innervate mouse spinal cord explants and evoke contractions of adjacent muscle in a manner dependent on intact organoid-derived innervating tracts. Overall, these results reveal a remarkable self-organization of corticofugal and callosal tracts with a functional output, providing new opportunities to examine relevant aspects of human CNS development and disease

Humidity-Sensing Properties of an 1D Antiferromagnetic Oxalate-Bridged Coordination Polymer of Iron(III) and Its Temperature-Induced Structural Flexibility

A novel one-dimensional (1D) oxalate-bridged coordination polymer of iron(III), {; ; [NH(CH3) (C2H5)2][FeCl2(C2O4)]}; ; n (1), exhibits remarkable humidity-sensing properties and very high proton conductivity at room temperature (2.70 × 10−4 (W·cm)−1 at 298 K under 93% relative humidity), in addition to the independent antiferromagnetic spin chains of iron(III) ions bridged by oxalate groups (J = −7.58(9) cm−1). Moreover, the time-dependent measurements show that 1 could maintain a stable proton conductivity for at least 12 h. Charge transport and magnetic properties were investigated by impedance spectroscopy and magnetization measurements, respectively. Compound 1 consists of infinite anionic zig-zag chains [FeCl2(C2O4)]nn− and interposed diethylmethylammonium cations (C2H5)2(CH3)NH+, which act as hydrogen bond donors toward carbonyl oxygen atoms. Extraordinarily, the studied coordination polymer exhibits two reversible phase transitions: from the high-temperature phase HT to the mid-temperature phase MT at T ~213 K and from the mid-temperature phase MT to the low-temperature phase LT at T ~120 K, as revealed by in situ powder and single-crystal X-ray diffraction. All three polymorphs show large linear thermal expansion coefficients

Learning ‘social responsibility’ in the workplace: conjuring, unsettling, and folding boundaries

This article proceeds from the argument that while the discourse of social responsibility (SR) is increasingly evident in pedagogies circulating through the workplace, its actual practices tend to be obscured beneath complex tensions and moral precepts presented as self-evident. Through an examination of individuals’ learning of SR in the workplace contexts of small enterprise, this discussion asks: How can we consider social responsibility in work, and the project of learning social responsibility in and for work, in more flexible ways that account for its complex enactments in pluralist contexts? The article explores dynamics of responsibility as both response and identity within literature on social responsibility in the workplace, and examines the process of learning SR as a matter of negotiating boundaries to enact response and identity. Drawing from findings of a qualitative study of 25 small enterprise owners engaging a process of learning SR practice, the article explores what are argued to be their boundary practices of conjuring, unsettling and folding boundaries as they developed viable locations and relations of social responsibility in their unique situations